1. Field of the Invention
The present invention relates to an image processing device, an image processing method, an image display device, and a recording medium storing a program for executing the image display method.
2. Description of the Related Art
When an enlarged image is output, in conventional image processing, edge enhancement is carried out to remove blur.
For example, in U.S. Patent Application Publication No. 2010/0134518, Moriya et al. disclose an image processing apparatus having a first image enlarging means that enlarges an input image and outputs a first enlarged image, a high-frequency component image generating means that extracts a high-frequency component of the input image and outputs a first high-frequency component image, a second image enlarging means that enlarges the first high-frequency component image and outputs a second enlarged image, a high-frequency component image processing means that extracts a high-frequency component from the image obtained by nonlinear processing on the second enlarged image and outputs a second high-frequency component image, and a means for adding the first enlarged image and the second high-frequency component image to output an enlarged image with enhanced edges.
Conventional image processing apparatus for output of enlarged images with enhanced edges tends to increase the values of pixels having values higher than the local average of the pixels around them, and decrease the values of pixels having values lower than the local average of the pixels around them.
This is done because increasing the values of pixels having values higher than the local average of the pixels around them and decreasing the values of pixels having values lower than the local average of the pixels around them can make edges sharper and eliminate blur in the enlarged image.
When the values of pixels having values higher than the local average of the pixels around them are increased and the values of pixels having values lower than the local average of the pixels around them are decreased, however, the result of this processing may look unnatural in areas lacking edges.
In textured areas, for example, increasing the values of pixels having values higher than the local average of the pixels around them and decreasing the values of pixels having values lower than the local average of the pixels around them divides the pixels into two classes, one having high values and the other having low values, so that fine patterns become indiscernible and the resolution appears to be reduced.